3 Types of Hip Impingement

The knees typically get the lion’s share of attention regarding joint pain. But hips can cause plenty of discomforts, too, and in many cases, those symptoms are caused by a condition called hip impingement.

Also known by its “medical” name, femoroacetabular impingement or FAI, hip impingement affects about 15% of Americans. Unless it’s treated early, it can lead to more chronic problems, like hip arthritis.

At his practice in Houston, Texas, Dr. Joshua Harris helps patients relieve hip impingement symptoms and improve the overall health and function of their hip joints. Here’s what he wants you to know about hip impingement, its causes, and treatment.

Hip anatomy 101

The hip joint is a ball and socket joint consisting of the rounded top of your thigh (femur) bone and the concave socket (acetabulum) in the pelvis. Hip movement depends on how the ball part (or the femoral head) interacts with the socket. When either the ball or the socket shape goes out of round is where problems can occur.

The surfaces of the femoral head and the acetabulum are covered with a thick layer of rubbery, slick cartilage. This joint cartilage layer protects the underlying bone while promoting smooth movement inside the joint. The cartilage and bone are like the tread on the tire in your car. In the situation of arthritis, the cartilage (or tread) is missing, and you’re riding on a bald rim.

In a typical, healthy hip joint, the ball fits snugly into the socket, held in place by ligaments and a strong ring of fibrous cartilage called the labrum. This is a different kind of cartilage than the joint cartilage. The labrum keeps the two parts of the joint in contact and helps your hip stay stable. The labrum essentially functions as a gasket seal, with a strong suction seal effect, to keep the ball stable in the socket throughout motion.

Types of hip impingement

Femoroacetabular impingement happens when the joint is misshapen - simply put, the round ball and socket shape is not round. There are three common causes or types of FAI: cam, pincer, and combined (both cam and pincer) FAI.

Cam impingement

Cam impingement is the most common type of hip impingement. It happens when the femoral head is misshapen, usually because of a “bump” of bone that forms where the head meets the top part of the femur (an area called the femoral neck) - “square peg in a round hole”. Cam impingement is the most common cause of labral tears. Cam impingement is the most common cause of hip arthritis.

Pincer impingement

Pincer impingement happens when the edge of the socket bone extends too far over the ball part of the joint. When you move your hip, the extended bone “pinches” the ball and prevents it from moving freely. Pincer impingement is often associated with tears of the labrum.

Combined impingement

This impingement happens when both the ball and socket portions are misshapen.

Causes of hip impingement

Most studies confirm that the cam type of hip impingement is developmental and acquired during adolescence. To date, there is little to no evidence suggesting a genetic or congenital cause of impingement. Cam impingement occurs much more frequently, up to 6-8 times, in athletes than non-athletes. The more athletes load the hip during their youth, the more the hip responds by forming bone. Literature suggests that more loading leads to a bigger bump, and less loading a smaller bump.

Cam impingement is a bony issue with extra bone, like a bone bump, a bone spur, or a “square peg in a round hole”. The bump begins as cartilage and turns into bone. It starts as cartilage around 8 years of age, and progressively enlarges and turns into bone maximally at around the age of 11 to 12 years, and slows down and is completed by around 16 years of age. 

Treating hip impingement

Some people have hip impingement and don’t even know it. Dr. Harris and others have published high-quality research showing the prevalence of impingement findings on medical imaging in both symptomatic and asymptomatic individuals, like x-rays, MRI’s, and CT’s. To date, there is no evidence supporting surgical treatment of asymptomatic individuals with abnormal imaging findings like cam or pincer impingement. This is why Dr. Harris frequently says “we treat patients, not x-rays”. This is also why it is so important to perform a thorough clinical examination in the office to see if a patient’s symptoms are from impingement or another cause. 

Many people experience pain in and around the hip joint or groin area, especially when they squat, turn, pivot, or twist. Stiffness and limping are also common, and symptoms feel worse during and after strenuous physical activity.

Dr. Harris uses a minimally invasive procedure called hip arthroscopy to evaluate and treat hip impingement. During the procedure, he uses special instruments to access the joint through tiny incisions. Then, he reshapes the ball and socket to eliminate impingement, improving symptoms and motion. Labral tears are also repaired during arthroscopy.

Hip arthroscopy is typically performed on an outpatient basis. Most patients begin physical therapy to strengthen the hip within 1 to 2 days of their procedure. Recovery takes about three to six months.

Don’t ignore hip pain

Hip impingement increases your risk of another chronic problem — hip arthritis. Having your hip pain evaluated and treated as early as possible is the best way to keep your hips healthy and functional. Although evidence is early, arthroscopic treatment of hip impingement may significant delay progression to hip arthritis.

To learn more about hip impingement and its treatment, book an appointment with Dr. Harris online or over the phone today.